Syntax error missing ; before *

最新推荐文章于 2022-08-04 22:53:00 发布

转载最新推荐文章于 2022-08-04 22:53:00 发布 · 742 阅读

文章标签：

#c/c++

本文探讨了一种常见的C++编程问题：头文件之间的循环依赖，并提供了解决方案。通过使用前向声明而非包含完整的头文件内容，可以有效避免此类错误。

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【问题】

I have a header file like so:

#pragma once

#include "gamestate.h"

#include "ExitListener.h"

class InitialGameState : public GameState

{

public:

InitialGameState(Ogre::Camera *cam, Ogre::SceneManager *sceneMgr, OIS::Keyboard *keyboard, OIS::Mouse *mouse, Ogre::Root *root);

~InitialGameState(void);

virtual bool update(Ogre::Real time);

virtual void pause(void);

virtual void start(void);

void keyPressed(const OIS::KeyEvent &e);

void keyReleased(const OIS::KeyEvent &e);

//private:

ExitListener *mFrameListener;

};

The problem with this is that I get the following errors from VC 8:

InitialGameState.h(16) : error C2143: syntax error : missing ';' before '*'

InitialGameState.h(16) : error C4430: missing type specifier - int assumed. Note: C++ does not support default-int

(they all refer to the last line)

I have a class ExitListener.h which is why I don't get the errors

Edit: ExitListener.h:

#pragma once

#include <Ogre.h>

#include <OIS/OIS.h>

#include <CEGUI/CEGUI.h>

#include <OgreCEGUIRenderer.h>

#include "Thing.h"

#include "InitialGameState.h"

using namespace Ogre;

class ExitListener : public FrameListener, public OIS::KeyListener, public OIS::MouseListener

{

public:

ExitListener(OIS::Keyboard *keyboard, OIS::Mouse *mouse, Camera *cam, std::vector<Thing*> &vec):

mKeyboard(keyboard), r(0.09), mContinue(true), mRunningAnimation(false),

mMouse(mouse), mYaw(0), mPitch(0), things(vec), mCamera(cam), mWDown(false), mSDown(false), mADown(false),

mDDown(false)

{

things = vec;

mKeyboard->setEventCallback(this);

mMouse->setEventCallback(this);

}

bool frameStarted(const FrameEvent& evt);

bool keyPressed(const OIS::KeyEvent &e);

bool keyReleased(const OIS::KeyEvent &e);

bool mouseMoved(const OIS::MouseEvent &e);

bool mousePressed(const OIS::MouseEvent &e, OIS::MouseButtonID id);

bool mouseReleased(const OIS::MouseEvent &e, OIS::MouseButtonID id);

void setOwner(GameState *g);

private:

AnimationState *mSwim;

Radian r;

Radian mYaw;

Radian mPitch;

OIS::Keyboard *mKeyboard;

OIS::Mouse *mMouse;

Camera *mCamera;

bool mContinue;

bool mRunningAnimation;

std::vector<Thing*> &things;

bool mWDown;

bool mADown;

bool mDDown;

bool mSDown;

GameState *mOwner;

};

Edit 2:

It turned out that the problem could be solved by a forward declaration and then including the other header directly in my .cpp file.

Thanks.

【答案】

My guess is that ExitListener.h is including InitialGameState.h header file either directly or indirectly. So there is a circular dependency between the header file and compiler is unable to find the declaration for ExitListener. If you just need to store the pointer of ExitListener in this class then there is no need to include the ExitListener.h header file. Instead you can just use the forward declaration as class ExitListener;

EDIT: You can use the forward declaration as suggested above, or remove the InitialGameState.h include from ExitListener.h . You need to include GameState.h (the base class header file) only. But I prefer to use the forward declarations in header file and include the header file only in cpp.

From: https://stackoverflow.com/questions/1542623/syntax-error-missing-before